1. Field of the Invention
The invention relates to networking. More specifically, the invention relates to traffic control in a distributed network.
2. Background
Routers in a traditional distributed network typically perform a routing function for a plurality of clients. Each client may send packets to be routed out over the internet, for example. A routing function is primarily a passthrough function and is dependent on egress bandwidth. When more packets come in than the router is able to send out during a particular time window, the packets are queued at the output of the router to wait for an available sending opportunity. If a backup in the pipe is sufficient that the queue reaches a predetermined threshold, the router institutes a drop policy to drop packets at the output interface when the queue is too full. Among the known drop policies are: Dynamic Window, Slow Start, and Nagles Algorithm. While these policies work satisfactorily, where, as in this example, the only resource at issue is output bandwidth, they are not satisfactory for allocation of other scarce resources, such as, Central Processing Unit (CPU) time in a multipurpose networking device.
A multipurpose network device such as, for example, a combination router and file server performs, Transmission Control Protocol/Internet Protocol (TCP/IP) routing functions, file server functions, management functions, and other activities based on incoming packets. These various activities must compete for shared resources within the device. As noted above, among the scarce shared resources are CPU time. While traditional systems allocate CPU time by task prioritization, task prioritization does not consistently provide desired and predictable performance.